In general, there is a need for a motor and a power source such as an engine for controlling a robot, a vehicle, a carrier, or a mechanical system and it is required to select the capacity of the power source to complete requested work (operation and action). For example, when a power source is a motor, the capacity of the motor is in close connection with the size, weight, and cost of the motor.
A power source with large capacity is required to operate a robot or a mechanical system with large torque at a high speed, so the size, weight, and cost of the robot or the mechanical system increase.
Vehicles are equipped with a gear shift system that changes a gear ratio when a rotational force from the engine is transmitted to wheels in order to achieve both of high-torque output for smooth driving on a slope and high-speed output for high-speed driving. However, such a gear shift system is difficult to apply to a small driving system due to a complicated mechanical configuration and problems with cost and weight.
Meanwhile, the applicant(s) has proposed a planetary gear system using two input characteristics in Korean Patent Application Publication No. 10-2012-0028234. However, the applicant(s) has proposed only a technology of combining input speeds in the application. Accordingly, there is a need for a gear system that can combine torque in addition to input speeds to achieve outputs with more various characteristics.
Therefore, the present invention proposes a technology that uses combinations of characteristic of different motors to achieve the characteristics of complicated mechanical system such as the gear shift system for automatic motor vehicles even without using the complicate mechanical system in order to be simply applied to a small motor system.
Further, the present invention provides a gear system that can be simply applied to a small driving system and generate various outputs by combining three or more inputs.